Rubber composition for sidewall and tire having sidewall using thereof, and rubber composition for clinch and tire having clinch using thereof

ABSTRACT

A rubber composition for a sidewall is disclosed, which includes a specific amount of an alkylphenol-sulfur chloride condensate indicated by the formula (B1): 
                         
and a specific filler, based on a rubber component including a specific amount of a natural rubber and/or an isoprene rubber and a modified butadiene rubber. A tire having the above sidewall is also disclosed.

TECHNICAL FIELD

The present invention relates to a rubber composition for sidewall and atire having sidewall using thereof, and a rubber composition for clinchand a tire having clinch using thereof.

BACKGROUND ART

It has been known that rolling resistance can be reduced by lowering thetan δ of a rubber composition used for the sidewall portion and clinchportion of a tire.

At that time, sulfur is used as a vulcanizing agent and a vulcanizationaccelerator is further used (for example, refer to Japanese UnexaminedPatent Publication No. 2006-63143). However, it is known that sulfur isdischarged at a final kneading step at low temperature anddispersibility is bad. Further, when the dispersion of sulfur is poor, arubber is ununiformly vulcanized and tan δ and fracture strength isdeteriorated.

Further, those such as HTS and PK900 available from Flexsys ChemicalsSdn. Bhd. and KA9188 available from Bayer AG that are hybridcrosslinking agents are used as an aid in order to suppress reversionand it is also known that a certain level of effect is obtained.However, although sulfur is partially included in HTS, fundamentalsolution is not carried out yet.

In order to solve the problem, methods such as oil treatment, the use ofinsoluble sulfur, the use of master batch of polymer and sulfur, and theuse of sulfur pellet chemical (obtained by blending sulfur and a binderrubber, for example, at a ratio of 50:50) are carried out.

Further, it is also known that an alkylphenol-sulfur chloride condensateis used as the crosslinking agent of a white rubber and a butyl rubberof a tire. The alkylphenol-sulfur chloride condensate is easilyscorched. Because the white rubber and butyl rubber have originally longscorch time, problems such as rubber scorch and surface bloom are notgenerated even if the alkylphenol-sulfur chloride condensate is used. Onthe other hand, since the scorch time of rubbers such as a naturalrubber usually used for sidewall and clinch is not so long as the whiterubber and a butyl rubber, there arises a problem such as rubber scorchduring processing when the alkylphenol-sulfur chloride condensate isused as a crosslinking agent. Further, when a large amount of PVI (aretarder CTP available from OUCHISHINKO CHEMICAL INDUSTRIAL CO., LTD.)being a vulcanization retarder is compounded, there arises a problemsuch as the surface bloom of PVI itself. Consequently, when thealkylphenol-sulfur chloride condensate is used for sidewall and clinch,on which surface bloom is not acceptable, the PVI is required to be usedfor suppressing scorch. And it has been considered that PVI cannot beused because of the surface bloom.

DISCLOSURE OF INVENTION

An object of the present invention to provide a rubber composition forsidewall and a tire having sidewall using thereof as well as a rubbercomposition for clinch and a tire having clinch using thereof thatsuppress scorch and surface bloom, reduce rolling resistance, can obtainsufficient rigidity as sidewall and clinch, and can improve elongationat break and durability.

A first aspect of the present invention relates to sidewall.

The first aspect of the present invention relates to a rubbercomposition for sidewall including 0.2 to 10 parts by weight of (B) analkylphenol-sulfur chloride condensate indicated by the formula (B1):

(wherein R¹ to R³ are same or different, each being an alkyl grouphaving 5 to 12 carbons; x and y are same or different, each being aninteger of 2 to 4; and n is an integer of 0 to 10) and 18 to 40 parts byweight of (C) at least one filler selected from a group comprising (C1)carbon black and (C2) silica, based on 100 parts by weight of (A) arubber component including 20 to 75% by weight of (A1) a natural rubberand/or an isoprene rubber and 20 to 75% by weight of (A2) a butadienerubber and/or an epoxidized natural rubber.

(A2) The butadiene rubber and/or epoxidized natural rubber is preferablya modified butadiene rubber.

The first aspect of the present invention also relates to a tire havingsidewall using the rubber composition for sidewall.

A second aspect of the present invention relates to clinch.

The second aspect of the present invention relates to a rubbercomposition for clinch including 0.2 to 10 parts by weight of (B) analkylphenol-sulfur chloride condensate indicated by the formula (B1):

(wherein R¹ to R³ are same or different, each being an alkyl grouphaving 5 to 12 carbons; x and y are same or different each being aninteger of 2 to 4; and n is an integer of 0 to 10) and 40 to 60 parts byweight of (C) at least one filler selected from a group comprising (C1)carbon black and (C2) silica, based on 100 parts by weight of (A) arubber component including 20 to 75% by weight of (A1) a natural rubberand/or an isoprene rubber and 20 to 75% by weight of (A2) a butadienerubber and/or an epoxidized natural rubber.

The rubber composition for clinch is preferable that the compoundingamount of (C2) silica is 10 to 15 parts by weight based on 100 parts byweight of the rubber component.

(A2) The butadiene rubber and/or epoxidized natural rubber is preferablya modified butadiene rubber.

The second aspect of the present invention also relates to a tire havingclinch using the rubber composition for clinch.

BEST MODE FOR CARRYING OUT THE INVENTION

Content common to the first aspect of the present invention relating tosidewall and the second aspect of the present invention relating toclinch is illustrated. The rubber composition for sidewall and therubber composition for clinch of the present invention include a rubbercomponent (A), an alkylphenol-sulfur chloride condensate (B) and filler(C).

The rubber component (A) includes a natural rubber (NR) and/or anisoprene rubber (IR) (A1) and a butadiene rubber (BR) and/or anepoxidized natural rubber (ENR) (A2).

As the NR, those such as RSS#3 grades that are general in the rubberindustry can be used. Also as the IR, those that are general in therubber industry can be used.

The content of the NR and/or IR (A1) in the rubber component (A) is atleast 20% by weight and preferably at least 30% by weight. When thecontent of the NR and/or IR (A1) is less than 20% by weight, strength atbreak is lowered. Further, the content of the NR and/or IR (A1) in therubber component (A) is at most 75% by weight and preferably at most 70%by weight. When the content of the NR and/or IR (A1) exceeds 75% byweight, crack growth resistance is deteriorated.

As the BR, those such as a high cis content butadiene rubber (high cisBR) and a modified butadiene rubber (modified BR) are listed.

In the present invention relating to sidewall and clinch, the butadienerubber and/or epoxidized natural rubber (A2) used for the rubbercomposition for sidewall and the rubber composition for clinch ispreferably a modified butadiene rubber, because rim chafing property canbe secured and low heat build-up is enabled.

The high cis BR is not particularly limited and those such as BR150Bmanufactured by Ube Industries Ltd., usually used in the rubberindustry, can be used.

The modified BR is not also particularly limited, but one is preferablethat is obtained by polymerizing 1,3-butadiene with a lithium initiatorand then adding a tin compound and where the terminal of the modified BRmolecule is bonded with a tin-carbon bonding.

The lithium initiator includes lithium compounds such as an alkyllithium, aryl lithium, vinyl lithium, organic tin lithium and organicnitrogen lithium compound, and lithium metal. The modified BR with highvinyl content and low cis content can be prepared by using the lithiuminitiator as the initiator of the modified BR.

The tin compound includes tin tetrachloride, butyltin trichloride,dibutyltin dichloride, dioctyltin dichloride, tributyltin chloride,triphenyltin chloride, diphenyl dibutyltin, triphenyltin ethoxide,diphenyl dimethyltin, ditolyltin chloride, diphenyltin dioctanoate,divinyl diethyltin, tetrabenzyltin, dibutyltin di-stearate,tetraallyltin, and p-tributyltin styrene. These tin compounds may beused alone and at least two kinds may be used in combination.

The content of a tin atom in the modified BR is preferably at least 50ppm and more preferably at least 60 ppm in the view point that effectfor promoting the dispersion of carbon black in the modified BR is greatand tan δ can be reduced. Further, the content of a tin atom ispreferably at most 3000 ppm, more preferably at most 2500 ppm andfurther preferably at most 250 ppm in the view point that thecohesiveness of a kneaded article is good and edges are arranged, andtherefore the extrusion processability of the kneaded article issuperior.

The molecular weight distribution (Mw/Mn) of the modified BR ispreferably at most 2 and more preferably at most 1.5 in the view pointthat the dispersibility of carbon black is superior and tan δ can bereduced. Further, the preferable lower limit of Mw/Mn is 1.

Further, as the BR, a butadiene rubber (SPB-including BR) including1,2-syndiotactic polybutadiene crystals can also be used in addition tothe high cis BR and the modified BR.

In the present invention, ENR is used when module other than petroleumis adopted.

As the ENR, a commercially available ENR may be used and ENR obtained byepoxidizing NR may be used. A method of epoxidizing NR is notparticularly limited and can be carried out using methods such as achlorohydrin method, a direct oxidation method, a hydrogen peroxidemethod, an alkylhydroperoxide method and a peracid method. For example,methods such as a method of reacting organic acids such as peraceticacid and performic acid with NR are listed.

The epoxidization ratio of the ENR is preferably 12 to 50% by mol in theview point that it is not compatible with NR and IR and rubber strengthis sufficiently obtained.

The content of the BR and/or ENR (A2) in the rubber component (A) is atleast 20% by weight and preferably at least 30% by weight. When thecontent of the BR and/or ENR (A2) is less than 20% by weight, crackgrowth resistance is deteriorated. Further, the content of the BR and/orENR (A2) in the rubber component (A) is at most 75% by weight andpreferably at most 70% by weight. When the content of the BR and/or ENR(A2) exceeds 75% by weight, strength at break is lowered.

As the rubber component (A), rubber components other than the NR and/orIR (A1) and the BR and/or ENR (A2) that have been conventionally usedusually in the rubber industry, such as a styrene-butadiene rubber(SBR), styrene-isoprene-butadiene rubber (SIBR), butyl rubber (IIR),halogenated butyl rubber (X-IIR), chloroprene rubber (CR),acrylonitrile-butadiene rubber (NBR) and ethylene-propylene-diene rubber(EPDM) can also be used. When these rubbers are used, they may be usedalone and at least two kinds may be used in combination, but theiramounts that do not alter the compounding amounts of the NR and/or IR(A1) and the BR and/or ENR (A2) and do not damage the effect of thepresent invention are preferable.

The rubber composition having sufficiently high hardness applicable forsidewall and clinch can be obtained by using the alkylphenol-sulfurchloride condensate (B) in the present invention.

The alkylphenol-sulfur chloride condensate (B) is used as thecrosslinking agent of a white rubber and a butyl rubber. Although thealkylphenol-sulfur chloride condensate is easily scorched, the problemof surface bloom is not generated even if the alkylphenol-sulfurchloride condensate is used, because the white rubber and butyl rubberhave originally long scorch time. On the other hand, since the scorchtime of rubbers such as a natural rubber usually used for sidewall andclinch is not so long as that of the white rubber and butyl rubber inlike manner as the present invention, there arises a problem such asrubber scorch during processing when the alkylphenol-sulfur chloridecondensate is used as a crosslinking agent; therefore a vulcanizationretarder cannot help being compounded and surface bloom caused by thevulcanization retarder compounded at this time causes a problem.Consequently, it has been considered that the alkylphenol-sulfurchloride condensate cannot be compounded in sidewall and clinch forwhich surface bloom by the vulcanization retarder cannot be approved,but in the present invention, even if the alkylphenol-sulfur chloridecondensate is applied to sidewall and clinch, scorch is not too short byadjusting the compounding amount of the filler (C); therefore theproblem of surface bloom is solved.

The alkylphenol-sulfur chloride condensate (B) is a compound indicatedby the formula (B1):

(wherein R¹ to R³ are same or different, each being an alkyl grouphaving 5 to 12 carbons; x and y are same or different, each being aninteger of 2 to 4; and n is an integer of 0 to 10).

n is preferably an integer of 0 to 10 and more preferably an integer of1 to 9 in the view point that the dispersibility of thealkylphenol-sulfur chloride condensate (B) in the rubber component (A)is good.

x and y are same or different, each is preferably an integer of 2 to 4and both are more preferably 2 in the view point that high hardness canbe efficiently exhibited (the suppression of reversion).

Each of R¹ to R³ is preferably an alkyl group having 5 to 12 carbons andmore preferably an alkyl group having 6 to 9 carbons in the view pointthat the dispersibility of the alkylphenol-sulfur chloride condensate(B) in the rubber composition (A) is good.

The alkylphenol-sulfur chloride condensate (B) can be prepared by knownmethods and its method is not particularly limited, but for example, amethod of reacting alkylphenol with sulfur chloride at a ratio of 1:0.9to 1.25 is listed.

As the specific example of the alkylphenol-sulfur chloride condensate(B), there is listed TACKROL V200 available from Taoka Chemical Co.,Ltd. in which n is 0 to 10, x and y are 2, R is C₈H₁₇ (octyl group) andthe content of sulfur is 24% by weight:

(wherein n is an integer of 0 to 10).

The compounding amount of the alkylphenol-sulfur chloride condensate (B)is at least 0.2 parts by weight and preferably at least 0.3 parts byweight based on 100 parts by weight of the rubber component (A). Whenthe compounding amount of the alkylphenol-sulfur chloride condensate (B)is less than 0.2 parts by weight, effect of improving rolling resistance(the reduction of tan δ) is not sufficiently obtained. Further, thecompounding amount of the alkylphenol-sulfur chloride condensate (B) isat most 10 parts by weight and preferably at most 9 parts by weightbased on 100 parts by weight of the rubber component (A). When thecompounding amount of the alkylphenol-sulfur chloride condensate (B)exceeds 10 parts by weight, scorch time is shortened and rubber scorchis generated during processing.

The filler (C) is at least one filler selected from a group comprisingcarbon black (C1) and silica (C2).

The carbon black (C1) is not particularly limited and grades such asSAF, ISAF, HAF, FEF and GPF, usually used in the rubber industry, can beused.

Further, the silica (C2) is not particularly limited and those preparedby a wet process or a dry process can be used.

The compounding amount of the filler (C) is illustrated in the firstaspect of the present invention relating to sidewall. In the rubbercomposition for sidewall, the compounding amount of the filler (C) is atleast 18 parts by weight and preferably at least 20 parts by weightbased on 100 parts by weight of the rubber component (A). In the rubbercomposition for sidewall in which the compounding amount of the filler(C) is less than 18 parts by weight, strength at break is insufficient,curbstone cut is generated and a problem is generated in durability.Further, the compounding amount of the filler (C) is at most 40 parts byweight and preferably at most 37 parts by weight based on 100 parts byweight of the rubber component (A). In the rubber composition forsidewall in which the compounding amount of the filler (C) exceeds 40parts by weight, tan δ is great and rolling resistance is also great.Further, at least 5 parts by weight of the carbon black (C1) ispreferably compounded for preventing deterioration by ultraviolet rays.

The compounding amount of the filler (C) is illustrated in the secondaspect of the present invention relating to clinch. In the rubbercomposition for clinch, the compounding amount of the filler (C) is atleast 40 parts by weight and preferably at least 43 parts by weightbased on 100 parts by weight of the rubber component (A). In the rubbercomposition for clinch in which the compounding amount of the filler (C)is less than 40 parts by weight, strength at break is insufficient,curbstone cut is generated and a problem is generated in durability.Further, the compounding amount of the filler (C) is at most 60 parts byweight and preferably at most 55 parts by weight based on 100 parts byweight of the rubber component (A). In the rubber composition for clinchin which the compounding amount of the filler (C) exceeds 60 parts byweight, tan δ is great and rolling resistance is also great. Further, atleast 5 parts by weight of the carbon black (C1) is preferablycompounded for preventing deterioration by ultraviolet rays.

Further, 10 to 15 parts by weight of silica (C2) in the rubbercomposition for clinch is preferably compounded for hardly generatingrubber scorch during processing.

When silica (C2) is used as the filler (C), a silane coupling agent ispreferably used in combination.

The silane coupling agent is not particularly limited, and those havingbeen conventionally used in combination with silica (C2) can be used.For example, there are listed sulfides such asbis(3-triethoxysilylpropyl)tetrasulfide,bis(2-triethoxysilylethyl)tetrasulfide,bis(4-triethoxysilylbutyl)tetrasulfide,bis(3-trimethoxysilylpropyl)tetrasulfide,bis(2-trimethoxysilylethyl)tetrasulfide,bis(4-trimethoxysilylbutyl)tetrasulfide,bis(3-triethoxysilylpropyl)trisulfide,bis(2-triethoxysilylethyl)trisulfide,bis(4-triethoxysilylbutyl)trisulfide,bis(3-trimethoxysilylpropyl)trisulfide,bis(2-trimethoxysilylethyl)trisulfide,bis(4-trimethoxysilylbutyl)trisulfide,bis(3-triethoxysilylpropyl)disulfide,bis(2-triethoxysilylethyl)disulfide,bis(4-triethoxysilylbutyl)disulfide,bis(3-trimethoxysilylpropyl)disulfide,bis(2-trimethoxysilylethyl)disulfide,bis(4-trimethoxysilylbutyl)disulfide,3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide,3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide,2-triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide,2-trimethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide,3-trimethoxysilylpropylbenzothiazolyltetrasulfide,3-triethoxysilylpropylbenzothiazoltetrasulfide, 3-triethoxysilylpropylmethacrylate monosulfide and 3-trimethoxysilylpropyl methacrylatemonosulfide; mercapto series such as 3-mercaptopropyltrimethoxysilane,3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane and2-mercaptoethyltriethoxysilane; vinyl series such as vinyltriethoxysilane and vinyl trimethoxysilane; amino series such as3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane,3-(2-aminoethyl)aminopropyl triethoxysilane, and3-(2-aminoethyl)aminopropyl trimethoxysilane; glycidoxy series such asγ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane,γ-glycidoxypropylmethyldiethoxysilane andγ-glycidoxypropylmethyldimethoxysilane; nitro series such as3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; chloroseries such as 3-chloropropyltrimethoxysilane,3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane and2-chloroethyltriethoxysilane.

In the rubber composition for sidewall, the compounding amount of thesilane coupling agent is preferably 4 to 10 parts by weight based on 100parts by weight of silica (C2) in the view point that silica isdispersed and high strength at break can be kept.

In the rubber composition for clinch, the compounding amount of thesilane coupling agent is preferably 2 to 10 parts by weight based on 100parts by weight of silica (C2) in the view point that silica isdispersed and high strength at break can be kept.

In the present invention, calcium stearate is preferably compounded whenENR is used as the rubber component (A).

In the rubber composition for sidewall, the compounding amount ofcalcium stearate is preferably 2 to 10 parts by weight based on 100parts by weight of ENR in the view point that the lowering of strengthat break during usage is prevented.

In the rubber composition for clinch, the compounding amount of calciumstearate is preferably 4 to 10 parts by weight based on 100 parts byweight of ENR in the view point that the lowering of strength at breakduring usage is prevented.

In the rubber composition for sidewall and the rubber composition forclinch of the present invention, there can be suitably compoundedcompounding agents conventionally used in the rubber industry, such asoil, stearic acid, an antioxidant, wax, zinc oxide, a vulcanizing agentsuch as sulfur, and various vulcanization accelerators if necessary, inaddition to the rubber component (A), the alkylphenol-sulfur chloridecondensate (B), the filler (C), the silane coupling agent and calciumstearate.

The compounding amounts of these other compounding agents are within arange not damaging the effect of the present invention by the rubbercomponent (A), the alkylphenol-sulfur chloride condensate (B) and thefiller (C).

The rubber composition for sidewall and the rubber composition forclinch of the present invention are prepared by a general method.Namely, the rubber composition for sidewall and the rubber compositionfor clinch of the present invention can be prepared by kneading therubber component (A), the alkylphenol-sulfur chloride condensate (B),the filler (C) and other compounding agents if necessary, with a Banburymixer, a kneader and an open roll and then, vulcanizing them.

The rubber composition for sidewall of the present invention is used asthe sidewall of a tire in the view point that strength at break, crackgrowth resistance and the property of low tan δ are pursued.

The rubber composition for clinch of the present invention is used asthe clinch of a tire in the view point that strength at break, crackgrowth resistance and the property of low tan δ are pursued.

The tire of the present invention is produced by a usual method usingthe rubber composition for sidewall and/or the rubber composition forclinch of the present invention. Namely, the rubber composition of thepresent invention compounding the compounding agents if necessary isextruded and processed in matching with the shape of the sidewall and/orclinch of a tire at an unvulcanization stage and molded on a tiremolding machine by a usual method; thereby an unvulcanized tire isformed. The unvulcanized tire is heated and pressurized in a vulcanizerto obtain a tire.

EXAMPLES

First, the present invention is specifically illustrated based onExamples in the first aspect of the present invention relating tosidewall, but the present invention is not limited only thereto.

Then, various chemicals used in Examples and Comparative Examples areillustrated in summary.

Natural rubber (NR): RSS#3.

Epoxidized natural rubber (ENR):ENR25 (epoxidization ratio: 25% by mol)manufactured by Kumpulan Guthrie Berhad

Modified butadiene rubber (modified BR): Nipol BR1250H (modified BR,lithium initiator: lithium, content of tin atom: 250 ppm, Mw/Mn: 1.5,and vinyl bonding amount: 10 to 13% by weight) manufactured by ZEONCorporation.

High cis content butadiene rubber (High cis BR): BR150B manufactured byUbe Industries Ltd.

Carbon black: SHOWBLACK N660 (GPF) available from CABOT JAPAN LTD.

Silica: 115GR available from RHODIA S.A.

Silane coupling agent: Si69 (bis(3-triethoxysilylpropyl)tetrasulfide)available from Degussa Huls Co.

Aromatic oil: PROCESS X-140 available from Japan Energy Co., Ltd.

Stearic acid: Stearic acid available from NOF Corporation.

Antioxidant: NOCRAC 6C(N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine) available fromOUCHISHINKO CHEMICAL INDUSTRIAL CO., LTD.

Wax: SUNNOC WAX available from OUCHISHINKO CHEMICAL INDUSTRIAL CO., LTD.

Zinc oxide: ZINC OXIDE available from Mitsui Mining And Smelting Co.,Ltd.

Calcium stearate: GF200 available from NOF Corporation.

Insoluble sulfur: Seimi sulfur (insoluble sulfur including at least 60%of insoluble content by carbon disulfide, and oil content: 10%)available from NIPPON KANRYU Industry Co., Ltd.

Vulcanization accelerator: NOCCELER NS (N-tert-butyl-2-benzothiazolylsulfenamide) available from OUCHISHINKO CHEMICAL INDUSTRIAL CO., LTD.

V200: TACKROL V200 (alkylphenol-sulfur chloride condensate, and n: 0 to10 in the formula below) available from Taoka Chemical Co., Ltd.

HTS: Sodium 1,6-hexamethylenedithio sulfate dihydrate available fromFlexsys Chemicals Sdn. Bhd.

PK900: PK900 (1,3-bis(citraconimide methyl)benzene) available fromFlexsys Chemicals Sdn. Bhd.

Examples 1 to 6 and Comparative Examples 1 to 6

Chemicals other than sulfur, a vulcanization accelerator and V200 werekneaded with a Banbury mixer according to the compounding prescriptionshown in Table 1 to obtain kneaded articles. Then, sulfur, avulcanization accelerator and V200 were added to the kneaded articlesobtained, and the mixture was kneaded with an open roll to obtainunvulcanized rubber compositions for sidewall. The resultantunvulcanized rubber compositions for sidewall were vulcanized bypressing under the condition of 170° C. for 12 minutes to prepare thevulcanized rubber compositions for sidewall of Examples 1 to 6 andComparative Examples 1 to 6.

(Curelasto Test)

Time T10 (min) at which torque was increased by 10% was measured at 160°C. by vulcanizing test pieces while applying vibration, using acurelastometer. T10 is preferably 2.0 to 5.0 minutes in order tosuppress rubber scorch and soddenness (such as bad adhesion) duringprocessing.

(Viscoelasticity Test)

The complex elastic modulus (E*) and loss tangent (tan δ) of thevulcanized rubber compositions was measured under the conditions of atemperature of 70° C., a frequency of 10 Hz, an initial stain of 10% anda dynamic strain of 2%, using a viscoelasticity spectrometer VES(manufactured by Iwamoto Seisakusyo K.K.). It is indicated that thelarger the E* is, the higher the rigidity is and the more superior thesteering stability is, and the smaller the tan δ is, the more superiorthe low fuel cost is.

(Tensile Test)

Tensile test was carried out according to JIS K 6251 “Vulcanized rubberand thermoplastic rubber—Determination method of tensile property”,using No. 3 dumbbell type test pieces made from the vulcanized rubbercompositions and elongation at break EB (%) was measured. It isindicated that the larger the EB is, the more superior it is.

(Heavy Load Durability Drum Test)

The unvulcanized rubber compositions were molded in a shape of sidewall,the molded articles were laminated with other tire members to formunvulcanized tires and they were vulcanized by pressing under conditionof 170° C. for 12 minutes to produce tires for test (size: 195/65R15).

The tires ran on a drum at a speed of 20 km/h under condition of amaximum load (maximum inner pressure condition) by JIS Specification of230% load and running distances until tires were damaged were measured.Then, the durability index of Comparative Example 1 was referred to as100 and the running distances of respective compoundings were displayedby indices according to the calculation formula below. Further, it isindicated that the larger the durability index is, the more superior thedurability is and the better it is.(Durability index)=(Running distance of each compounding)/(Runningdistance of Comparative Example 1)×100

The evaluation results of the fore-mentioned tests are shown in Table 1.

TABLE 1 Examples Comparative Examples 1 2 3 4 5 6 1 2 3 4 5 6Compounding amount (parts by weight) NR 60 60 60 60 60 60 60 60 60 60 6060 ENR — — — — 40 — — — — — — — Modified BR 40 40 — 40 — 40 40 40 40 4040 40 High cis BR — — 40 — — — — — — — — — Carbon black 30 30 30 22 3010 30 50 30 30 15 30 Silica — — — — — 20 — — — — — — Silane couplingagent — — — — — 1.6 — — — — — — Aromatic oil 6 6 6 6 6 6 6 6 6 6 6 6Stearic acid 2 2 2 2 2 2 2 2 2 2 2 2 Antioxidant 3 3 3 3 3 3 3 3 3 3 3 3Wax 1 1 1 1 1 1 1 1 1 1 1 1 Zinc oxide 4 4 4 4 4 4 4 4 4 4 4 4 Calciumstearate — — — — 3 — — — — — — — Insoluble sulfur 2.11 1.88 2.11 2.112.11 2.11 2.33 2.11 2.11 2.11 2.11 1.88 (Content of pure (1.9) (1.7)(1.9) (1.9) (1.9) (1.9) (2.1) (1.9) (1.9) (1.9) (1.9) (1.7) sulfur)Vulcanization 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1accelerator V200 1 2 1 1 1 1 — 1 — — 1 15 HTS — — — — — — — — 1 — — —PK900 — — — — — — — — — 1 — — Evaluation result T10 2.5 2.3 2.5 2.7 2.42.8 4.4 1.6 4.1 4.4 3.2 0.8 E* 4.0 4.1 4.1 3.2 4.3 3.3 4.0 5.2 3.7 3.72.8 5.9 tanδ 0.085 0.083 0.115 0.066 0.105 0.093 0.092 0.121 0.094 0.0930.052 0.060 EB (%) 400 405 420 350 370 350 350 400 390 400 300 220Durability index 140 110 100 120 100 170 100 60 120 120 40 50

Then, the present invention is specifically illustrated based onExamples in the second aspect of the present invention relating toclinch, but the present invention is not limited only thereto.

Then, various chemicals used in Examples and Comparative Examples areillustrated in summary.

Natural rubber (NR): RSS#3.

Modified butadiene rubber (modified BR): Nipol BR1250H (modified BR,lithium initiator: lithium, content of tin atom: 250 ppm, Mw/Mn: 1.5 andvinyl bonding amount: 10 to 13% by weight) manufactured by ZEONCorporation.

High cis content butadiene rubber (High cis BR): BR150B manufactured byUbe Industries Ltd.

Carbon black: SHOWBLACK N330 (HAF) available from CABOT JAPAN LTD.

Silica: 115GR available from RHODIA S.A.

Silane coupling agent: Si69 (Bis(3-triethoxysilylpropyl)tetrasulfide)available from Degussa Huls Co.

Aromatic oil: PROCESS X-140 available from Japan Energy Co., Ltd.

Stearic acid: Stearic acid available from NOF Corporation.

Antioxidant: NOCRAC 6C(N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine) available fromOUCHISHINKO CHEMICAL INDUSTRIAL CO., LTD.

Wax: SUNNOC WAX available from OUCHISHINKO CHEMICAL INDUSTRIAL CO., LTD.

Zinc oxide: ZINC OXIDE available from Mitsui Mining And Smelting Co.,Ltd.

Calcium stearate: GF200 available from NOF Corporation.

Insoluble sulfur: Seimi sulfur (insoluble sulfur including at least 60%of insoluble content by carbon disulfide, and oil content: 10%)available from NIPPON KANRYU Industry Co., Ltd.

Vulcanization accelerator: NOCCELER NS (N-tert-butyl-2-benzothiazolylsulfenamide) available from OUCHISHINKO CHEMICAL INDUSTRIAL CO., LTD.

V200: TACKROL V200 (alkylphenol-sulfur chloride condensate, and n: 0 to10 in the formula below) available from Taoka Chemical Co., Ltd.

PVI: Retarder CTP available from OUCHISHINKO CHEMICAL to INDUSTRIAL CO.,LTD.

Examples 7 to 12 and Comparative Examples 7 to 11

Chemicals other than sulfur, a vulcanization accelerator, V200 and PVIwere kneaded with a Banbury mixer according to the compoundingprescription shown in Table 2 to obtain kneaded articles. Then, sulfur,a vulcanization accelerator, V200 and PVI were added to the kneadedarticles obtained, and the mixture was kneaded with an open roll toobtain unvulcanized rubber compositions for clinch. The resultantunvulcanized rubber compositions for clinch were vulcanized by pressingunder the condition of 170° C. for 12 minutes to prepare the vulcanizedrubber compositions for clinch of Examples 1 to 6 and ComparativeExamples 1 to 5.

(Curelasto Test)

Time T10 (min) at which torque was increased by 10% was measured at 160°C. by vulcanizing test pieces while applying vibration, using acurelastometer. When T10 is less than 2.2 minutes, rubber scorch isgenerated during extrusion processing.

(Viscoelasticity Test)

The complex elastic modulus (E*) and loss tangent (tan δ) of thevulcanized rubber compositions was measured under the conditions of atemperature of 70° C., a frequency of 10 Hz, an initial stain of 10% anda dynamic strain of 2%, using a viscoelasticity spectrometer VES(manufactured by Iwamoto Seisakusyo K.K.). The E* is preferably about6.0 to 8.0 in order to prevent contact with a rim and abrasion.

(Tensile Test)

Tensile test was carried out according to JIS K 6251 “Vulcanized rubberand thermoplastic rubber—Determination method of tensile property”,using No. 3 dumbbell type test pieces comprising the vulcanized rubbercompositions and elongation at break EB (%) was measured. It isindicated that the larger the EB is, the more superior it is.

(Heavy Load Durability Drum Test)

The unvulcanized rubber compositions were molded in a shape of clinch,the molded articles were laminated with other tire members to formunvulcanized tires and they were vulcanized by pressing under conditionof 170° C. for 12 minutes to produce tires for test (size: 195/65R15).

The tires ran on a drum at a speed of 20 km/h under condition of amaximum load (maximum inner pressure condition) by JIS Specification of230% load and running distances until tires were damaged were measured.Then, the durability index of Comparative Example 7 was referred to as100 and the running distances of respective compoundings were displayedby indices according to the calculation formula below. Further, it isindicated that the larger the durability index is, the more superior thedurability is and the better it is.(Durability index)=(Running distance of each compounding)/(Runningdistance of Comparative Example 7)×100

The evaluation results of the fore-mentioned tests are shown in Table 2.

TABLE 2 Examples Comparative Examples 7 8 9 10 11 12 7 8 9 10 11Compounding amount (parts by weight) NR 35 35 35 35 35 35 35 35 35 35 35Modified BR 65 65 — 65 65 — 65 65 65 — 65 High cis BR — — 65 — — — — — —65 — ENR — — — — — 65 — — — — — Carbon black 32 44 32 32 42 32 32 44 5032 32 Silica 12 — 12 12 12 12 12 — 12 12 12 Silane coupling agent 0.96 —0.96 0.96 0.96 0.96 0.96 — 0.96 0.96 0.96 Aromatic oil 3 3 3 3 3 3 3 3 33 3 Stearic acid 2 2 2 2 2 2 2 2 2 2 2 Antioxidant 2 2 2 2 2 2 2 2 2 2 2Wax 1 1 1 1 1 1 1 1 1 1 1 Zinc oxide 3 3 3 3 3 3 3 3 3 3 3 Calciumstearate — — — — — 4 — — — — — Insoluble sulfur 2.56 2.56 2.56 2.33 2.332.56 2.78 2.78 2.33 2.78 2.33 (Content of pure sulfur) (2.3) (2.3) (2.3)(2.1) (2.1) (2.3) (2.5) (2.5) (2.1) (2.5) (2.1) Vulcanizationaccelerator 2.4 2.4 2.4 2.4 2.0 2.4 2.4 2.4 2.0 2.4 2.4 V200 1.0 1.0 1.02.0 1.0 1.0 — — 1.0 — 15 PVI 0.4 0.4 0.4 0.6 0.6 0.4 — — 0.4 — 0.6Evaluation result T10 3.2 2.3 3.3 2.2 2.5 2.3 3.0 2.0 1.7 3.1 0.6 E* 6.36.8 6.4 6.4 6.5 6.5 6.3 6.9 7.8 6.3 9.3 tanδ 0.098 0.110 0.135 0.0940.118 0.133 0.120 0.124 0.130 0.151 0.083 EB(%) 320 280 350 305 380 340290 200 230 330 160 Durability index 140 110 90 140 120 105 100 70 65 6050

INDUSTRIAL APPLICABILITY

According to the present invention, there can be provided a rubbercomposition for sidewall and a tire having sidewall using thereof aswell as a rubber composition for clinch and a tire having clinch usingthereof that suppress scorch and surface bloom, reduce rollingresistance, can obtain adequate rigidity as sidewall and clinch and canimprove elongation at break and durability, by including the specificamounts of the specific rubber component (A), the specificalkylphenol-sulfur chloride condensate (B) and the specific filler (C).

The invention claimed is:
 1. A rubber composition for sidewallcomprising 0.2 to 2 parts by weight of (B) an alkylphenol-sulfurchloride condensate indicated by the formula (B1):

wherein R¹ to R³ are same or different, each being an alkyl group having8 carbons; x and y are same or different, each being an integer of 2 to4; and n is an integer of 0 to 10 and 18 to 40 parts by weight of (C) atleast one filler selected from the group consisting of (C1) carbon blackand (C2) silica, based on 100 parts by weight of (A) a rubber componentconsisting of 30 to 70% by weight of (A1) a natural rubber and/or anisoprene rubber and 30 to 70% by weight of (A2) a modified butadienerubber.
 2. The rubber composition for sidewall of claim 1, wherein (A2)the modified butadiene rubber is obtained by polymerizing 1,3-butadienewith a lithium initiator and then adding a tin compound wherein theterminal of the modified butadiene rubber molecule is bonded with atin-carbon bonding.
 3. A tire having a sidewall comprising the rubbercomposition for sidewall of claim 1.